What type of cataract is characterized by a fully developed opacity of the lens with fluid generation?

A hypermature cataract is characterized by significant changes in the lens, leading to a fully developed opacity accompanied by fluid accumulation. In this stage, the lens may become shrunken and dense, often with the formation of a liquid interface due to the breakdown of lens fibers and the movement of water into the lens. The clarity of vision is severely impaired due to this pronounced opacity, which can also result in complications such as lens leakage.

In contrast, congenital cataracts typically occur at birth or develop during infancy, often not exhibiting the fluid characteristics seen in hypermature cataracts. Nuclear cataracts primarily affect the central zone of the lens and tend to develop gradually over time, leading to increased density and a cloudy lens, but they do not present with the same level of fluid generation. Posterior subcapsular cataracts form at the back of the lens and affect vision by causing glare and impaired vision in bright light, but this type also does not exhibit the fluid accumulation characteristic of hypermature cataracts.

Overall, the presence of fully developed lens opacity along with fluid generation distinctly defines a hypermature cataract, making it the correct response when considering the clinical features outlined in the question.